The study presented by [1]} suggests that, although both light and heavy seeds are able to form along the hierarchical assembly of a \(z>6\)  QSO, the growth of the SMBH in an Eddington-limited gas accretion regime relies on the formation of few heavy seeds at \(z\sim 16-18\)  (from 3 to 30, according to the specific halo merger tree).
